I'm aware of the following site-to-site VPN limitation: Note: Non-Meraki VPN peers are organization-wide, so peers will be configured for all such MX devices in an organization. If you want multiple MX's to connect to the same 3rd party VPN peer they will all have the same shared secret.
The security policy of the multi-site deployment I'm currently working on requires different preshared secrets for all branch sites, which is obviously a problem. Does anyone know if this is on a roadmap for future enhancement?